ANSI SMPTE ST 234-1998 Motion-Picture Film (8-mm Type R) - Projectable Image Area and Projector Usage.pdf

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1、STD-SMPTE 234-ENGL 3778 D 8357403 0003038 272 D SMPTE STANDARD ANSVSMPTE 234-1 998 evisionn of ANSI/SMPTE 234-1993 for Motion-Picture Film (8-mm Type R)- Projectable Image Area and Projector Usage 1 Scope 1.1 This standard specifies the maximum dimen- sions of the film image area intended for projec

2、- tion from an 8-mm type R motion-picture film, and the placement of this area relative to the perforations and the reference edge of the film. 1.2 This standard also specifies the position of the emulsion, the rate of projection, and the orientation of the image area for 8-mm type R motion- picture

3、 film as used in a motion-picture projector. Page 1 of 3 pages photography for final viewing because it pre- sents a description of the picture area on the projection print that is usable for the indicated purposes of the print which is of primary impor- tance because the projection print is the mos

4、t commonly interchanged item. 4.2 ANSVSMPTE 231 defines the image area for other important phases of motion-picture opera- tions, and it is consistent with this standard under currently acceptable commercial practice. 5 Emulsion position 2 Normative reference The following standard contains provisio

5、ns which, through reference in this text, constitute provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revi- sion, and parties to agreements based on this stand- ard are encouraged to investigate the possibility of applying the mos

6、t recent edition of the standard indi- cated below. ANSVSMPTE 239-1 995, Motion-Picture Film (1 6-mm)-Perforated 8-mm Type RI 2R 3 Dimensions 3.1 The dimensions shall be as given in figure 1 and table 1. 3.2 The angle between the horizontal edges of the image area and the reference edge of the film

7、shall be 90“ k Mo. 4 Relationship to other standards 4.1 This standard may be used as the basis for establishing picture areas from original Most 8-mm films are projected with the emulsion toward the screen. There are, however, some systems which produce prints that are projected with the base towar

8、d the screen. 6 Rate of projection The normal rate of projection shall be 18 frames per second for silent film and 24 frames per second for sound film. NOTES 1 Camera and printer apertures. The actual image on the film is significantly larger than the maximum area intended for projection, so that in

9、 placement of the images throughout the sequence of the films the tolerance is not restrictive of commercial practice. Upper limits have been established through consideration of good practice in avoiding frame overlap, encroachment upon areas reserved for audio re- cords, flare from perforation edg

10、es, etc. Lower limits are similarly related to the avoidance of image effects at a defined edge, tolerances in film position, etc. 2 Projector aperture. Dimensions B, D, and E define the maximurn image area on the film that is available for projec- tion. They do not define the opening in the apertur

11、e plate of CAUTION NOTICE: This Standard may be revised or withdrawn at any time. The procedures of the Standard Developer require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of publication. Purchasers of standards may receive current in

12、formation on e11 standards by calling or writing the Standard Developer. Printed in USA. L American National Standard Copyrighi O 1998 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Harisdale Ave., White Plains, NY 10607 (914) 761 -1 1 O0 Approved August 18,1998 ANSVCMPTE 234-1998

13、a projector. The size of this opening may differ from dimen- sions A and B, for example, because of the physical sepa- ration necessary between the aperture plate and the film to avoid scratching the film, the slant of the marginal rays accepted by the projection lens, etc. 3 Actual projected area.

14、It is recognized that, in many cases, the actual film image area that is projected may be smaller than the projectable maximum and, in some cases, may be nonrectangular (for example, an irregular four-sided figure bound by either straight or curved lines). Such depar- tures may result from equipment

15、 considerations such as slight inconsistencies among lenses, screen sizes, etc.; from geometric limitations such as the screen surface being at an angle other than 90“ from the projection axis, or being nonplanar, or both; and from aesthetic considerations such as pictorial composition within more r

16、estrictive image limits. In the absence of specific instructions to the contrary, it is intended that the actual projected film image area be the largest appropriately-shaped figure that can be inscribed within the specified dimensions. When the picture outline on the screen is defined by the projec

17、tor aperture, it is customary to round the comers of the projected film area. A maximum corner radius of 0.01 O in (0.25 mm) at the film plane is recommended. 4 Film perforations. Film intended for projection with this image area is normally perforated as specified in ANSVSMPTE 231. I I I- l FILM IM

18、AGE AREA-i J Q OF FILM K IMAGE AREA PROJECTABLE IMAGE AREA -+A REF ERENCE EDGE PROJECTABLE IMAGE AREA Figure 1 - Projectable image area on film as seen looking through the film toward the lens Table 1 - Dimensions Dimensions Inches Mil limete rs A 0.172 non 4.37 nom B 0.130 max 3.30 max C* 0.205 ref

19、 5.21 ref D 0.1 17 min 2.97 min E 0.293 max 7.44 max F=H within 0.014 within 0.36 J=K nominally equal nominally equal * See A.l Page 2 of 3 pages STD-SMPTE 234-ENGL 1978 m 83574U3 00030LiO 720 m ANSVSMPTE 234-1998 LIGHT BEAM GF TRAVEL Figure 2 - Film as seen from projector light source looking towar

20、d lens Annex A (informative) General information A.l The centerlines of the image area are given for conven- ience in interpreting the standard, facilitating such applica- tions as the optical design of equipment, and assisting in the understanding of suitable mechanical embodiments related to the p

21、rojectable image areas. Note that the centerline of the projectable image area is displaced from the centerline of the film by 0.048 in (1.22 mm) nominal. Annex B (informative) Bibliography A.2 Because of the increased intensity of illumination avail- able in modern 8-mm projection systems, the indu

22、stry has found it desirable to extend the flicker threshold by choosing as high a projection rate (and, therefore, as high a flicker frequency) as practicable. A projection rate of 18 frames per second and a corresponding flicker frequency of 54 cycles per second (obtained with a three-blade shutter) have been found by experience to be an acceptable compromise. ANSIISMPTE 231 -1 995, Motion-Picture Film (8-mm Type R) - Camera Aperture Image and Usage Page 3 of 3 pages